A roof system generally includes a roof deck that is considered the structural supporting surface of a building extending between surrounding exterior walls of the building. The roof deck may be constructed from plywood, metal decking or concrete or any other suitable material. Depending upon the construction, the roof deck may extend over the surrounding exterior walls or the roof deck may stop short of the exterior walls thereby forming a parapet wall, i.e., a low retaining wall at the edge of the roof deck. If desired, the roofing system may also include an insulation barrier formed from polyisocyanurate or any other suitable material applied over the roof deck.
To make the roof system weather resistant, a single-ply membrane roof may be installed over the roof deck. A single-ply membrane roof refers to a water impermeable single sheet of polymeric material such as thermoplastic olefins, chlorinated polyethylene, polyvinyl chloride, chlorosulfonasted polyethylene or ethylene propylene diene rubber (EPDM). The membrane roof may be mechanically fastened over the roof deck using a variety of different methods well known in the art.
When applying the membrane roof to the roof deck, it is usually necessary to splice together roofing membranes to form a single continuous field of the membrane roof An example of this would be cured EPDM sheets. It will be appreciated that the splice or seam area is subjected to both short term and long term stresses such as those caused by roof movement, heavy winds, freeze thaw cycling and thermal cycling. Such stresses may manifest themselves in shear forces or peel forces, i.e., the seam peels back under severe stress conditions or may cause a partially open seam under less severe conditions.
In view of the foregoing problem, it has been necessary to apply an adhesive to splice the cured EPDM roofing membranes together. The adhesive for splicing cured EPDM roofing membranes together must be capable of being simply and/or economically applied in the field to provide an acceptable adhesive bond. The applied adhesive must provide sufficient seam peel and shear strength such that the spliced EPDM roofing membranes resist both the short term and long term stresses. Moreover, the applied adhesive must be resistant to oxidation, hydrolysis and chemical attack from pooled water.
In accordance with one object of the present invention, an apparatus is provided for continuously applying TPO or TPE adhesive between talc-free overlapping edges of roofing membranes (e.g. EPDM sheets). In accordance with another object of the present invention, an apparatus is provided for continuously applying a TPO (thermoplastic olefin) or TPE (thermoplastic elastomer) adhesive between overlapping edges of EPDM roofing membranes. It is another object of the present invention to provide an applicator for applying a TPO or TPE adhesive between overlapping single-ply EPDM roof membranes to form a seam in the field. Yet another object of the present invention is to provide an applicator and method for applying a TPO or TPE adhesive that is simple to use and economical to manufacture.